Very possible but it does not impact the renewal process. USCIS will conduct an independent review when adjudicating your application.

Can I be my own co-sponsor (form I-864A) If I have been filing taxes for the last 15 years BUT I get a refund every year?

Yes your income can be considered. Review the requirements for eligible income in the instructions to the form I 864.

Is my child in status?

Once married she is no longer considered your dependent and needs to have status based on her own eligibility.

L1A risk ?

Assuming you and the employee meet all of the requirements one year employment abroad in a position that meeting the USCIS qualifications as a...

Can my mother deport me even though im 18 and have my green card?

As a permanent resident of the United States and being of the age of majority 18 you are welcome to remain in the United States.

Can I apply for J-2 VISA stamping from my home country while my Partner J-1 waiver (212e) is under process in the USA ?

Having a waiver pending should not impact the J2 status or visa stamping if your partner is in Valid J1 status.

The proposed marriage does not impact the naturalization process.

If detected by the US consulate which is likely you should be barred from obtaining a visa. A waiver may be possible.

Yes have the record corrected. You may do so at the CBP location nearest to you. You will need to check with the local office to learn their...

Not a recommended strategy. Wait for a decision on the waiver.